Thomas a



(No Model.)

T. A. EDISON.

MANUFACTURE OF GARBONS FOR ELECTRIC LAMPS. No. 248,416. Patented Oct.18,1881.

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l l l t NITED STATES PATENT OFFICE.

THOMAS A. EDISON, OF MENLO PARK, NEW JERSEY, ASSIGNOR- TO THE EDISONELECTRIC LIGHT COMPANY, OF NEW YORK, N. Y.

MANUFACTURE OF CARBONS FOR ELECTRIC LAMPS.

SPECIFICATION forming part of Letters latent No. 248,416, dated October18, 1881.

I Application filed January 11, 1881. (No model.)

To all whom it may concern: I

Be it known that I, THOMAS A. EDIsoN, of Menlo Park, in the county ofMiddlesex and State of New Jersey, have invented a new and usefulImprovement in the Manufacture of Garbons for Electric Lamps; and I dohereby declare that the following is a full and exact description of thesame, reference being bad to the accompanying drawing, and to theletters of reference marked thereon.

In the carbon filaments of incandescent electric lamps there aresometimes found weak or defective spots. Some method is thereforedesirable by means of which carbon may be deposited at such a point tobuild it up, so that its resistance will be the same as that of the restof the filament.

The object of this invention is to provide a method and apparatus foraccomplishing this purpose; and to this end it consists in heating thecarbon by focusing on the detective point the rays from an externalsource of heat, as the sun or a voltaic-arc lamp, while at the same timea carbon vapor from heated naphthaline crystals or other carbon compoundwhich is solid at ordinary temperatures is forced into the globe whichcontains the carbon filament, and from which the air has been exhausted.The vapor will deposit carbon on the heated point, which will thenbecome a part ot'thecar-V bon filament.

The accompanying drawing is a view in section of an appropriateapparatus for this purpose.

A is the incaudescing electric lamp, containing the carbon filament B,which has been found detective at the point a;

O is the mercury-drop for forming the vacuum in the lamp.

D is a glass bulb connected with the lamp by the tube 1). It containscrystals of naphthaline, or other caibon compound of a similar nature,and it may be heated by means of the lamp E.

F is avoltaic-arc lamp, the rays from which, by means of the reflectorsc and d, may be focused upon the defective point a of the carbon B.

Heat being applied to the bulb which contains the carbon compound, it isvolatilized,

and the vapor passes through the tube b into the lamp, where it depositsan amount of carbon on the heated point of the filament. The rest of thevapor is then removed by means of the mercury-drop. I

It is ObVlOUS that sources of heat other than that described, includingthe rays of the sun, may be used.

If desired, a small amount of naphthaline crystals maybe placed in thebottom of the inclosing-globe ot' the lamp, which will, when the lamp,isin use, become heated and volatilize, supplying the waste ot'ca'rhon dueto the process known as electrical carrying. Such crystals H are shownplaced in the bottom of the lamp, where they will be subjected to only avery moderate heat, yet a heat satficient for the purpose. The lamp issealed off at w, and is then ready for use.

What I claim as my invention is--- 1. The within-described process ofbuilding up or strengthening a defective point in an incandescingconductor for electric lamps, consisting in heating that point to a hightemperature by concentrating thereon the heat from an external source,and at the same time allowing a carbon vapor to enter the globe anddeposit additional carbon on the heated point, substantially as setforth.

2. The apparatus for building up or repairing detective carbonfilaments, consisting of a separate vessel containing a solidhydrocarbon compound volatilizable at low heat, means for passing thevapor into the chamberot the lamp containing the carbon filament, andmeans for raising any desired portion of the filament to a hightemperature by concentrating or focus ing upon said portion rays ofheat, substantially as shown and described.

3. An electric lamp consisting of a globe in- 0 closing a carbonfilament and conductingwires, and arranged to contain a portion of asolid compound of carbon volatilizable at low heat, substantially asshown and described.

This specification signed and witnessed this 30th day of December, 1880.

THOS. A. EDISON.

IVitnesses:

H. W. SEELY, ERNEST J. BERGGREN.

